Breaking the Stream Ciphers F-FCSR-H and F-FCSR-16 in Real Time

The F-FCSR stream cipher family has been presented a few years ago. Apart from some flaws in the initial propositions, corrected in a later stage, there are no known weaknesses of the core of these algorithms. Two variants, F-FCSR-H and F-FCSR-16, were proposed in the eSTREAM project, and F-FCSR-H v2 is one of the ciphers selected for the eSTREAM portfolio.     

Influence of N doses and form on ¹⁵N natural abundance of pepper plants: considerations for using δ¹⁵N values as indicator of N source

BACKGROUND: The aim of this study was to ascertain the effect of the N form (NO₃^?, NH₄⁺ and organic N) and N concentration on plant isotopic fractionation and on the contribution of the different N sources to the plant N budget, in order to evaluate the feasibility of using plant δ¹⁵N values for discriminating between conventional and organic crops. To this end, different N concentrations (applied as NO₃^?), N forms (NO₃^? versus NH₄⁺), and increasing NO₃^? applications to an organic N‐based fertilization regime were studied. RESULTS: When using NO₃^? as N source, intra‐plant fractionation was significant and tended to increase when NO₃^? concentration increased in the root medium. However, negligible net isotopic fractionation was observed when comparing theoretical and measured plant δ¹⁵N values. On the other hand, when plants are fertilized with a mixture of NO₃^? and NH₄⁺, differences in uptake patterns for both salts could result in variation in plant δ¹⁵N regarding to the expected value. Finally, the application of NO₃^? to plants was detected when it was combined with high levels of organic N sources, from 99:1 organic:inorganic N ratio. CONCLUSION: Under certain conditions and following some considerations concerning sampling, δ¹⁵N values can be considered to be a potential tool to guarantee the authenticity of organic products. Copyright © 2011 Society of Chemical Industry     

An Efficient State Recovery Attack on the X-FCSR Family of Stream Ciphers

We describe a state recovery attack on the X-FCSR family of stream ciphers. In this attack we analyse each block of output keystream and try to solve for the state. The solver will succeed when a number of state conditions are satisfied. For X-FCSR-256, our best attack has a computational complexity of only 2^4.7 table lookups per block of keystream, with an expected 2^44.3 such blocks before the attack is successful. The precomputational storage requirement is 2³³. For X-FCSR-128, the computational complexity of our best attack is 2^16.3 table lookups per block of keystream, where we expect 2^55.2 output blocks before the attack comes through. The precomputational storage requirement for X-FCSR-128 is 2⁶⁷.     

A Simple Environmentally-friendly Method for the Selective Synthesis of 1,5-benzodiazepine Derivatives using Zeolite Catalyst

The modified small pore size zeolite E4a has been found to be an efficient catalyst for the regioselective synthesis of 2,3-dihydro-1H-1,5-benzodiazepines from o-phenylenediamine and ketones. This method is simple, cheap, environmentally-friendly and give the benzodiazepines in high yield.     

SAP97 is associated with the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor GluR1 subunit

Rapid glutamatergic synaptic transmission is mediated by ionotropic glutamate receptors and depends on their precise localization at postsynaptic membranes opposing the presynaptic neurotransmitter release sites. Postsynaptic localization of N-methyl-D-aspartate-type glutamate receptors may be mediated by the synapse-associated proteins (SAPs) SAP90, SAP102, and chapsyn-110. SAPs contain three PDZ domains that can interact with the C termini of proteins such as N-methyl-D-aspartate receptor subunits that carry a serine or threonine at the -2 position and a valine, isoleucine, or leucine at the very C terminus (position 0). We now show that SAP97, a SAP whose function at the synapse has been unclear, is associated with alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)-type glutamate receptors. AMPA receptors are probably tetramers and are formed by two or more of the four AMPA receptor subunits GluR1-4. GluR1 possesses a C-terminal consensus sequence for interactions with PDZ domains of SAPs. SAP97 was present in AMPA receptor complexes immunoprecipitated from detergent extracts of rat brain. After treatment of rat brain membrane fractions with the cross-linker dithiobis(succinimidylpropionate) and solubilization with sodium dodecylsulfate, SAP97 was associated with GluR1 but not GluR2 or GluR3. In vitro experiments with recombinant proteins indicate that SAP97 specifically associates with the C terminus of GluR1 but not other AMPA receptor subunits. Our findings suggest that SAP97 may be involved in localizing AMPA receptors at postsynaptic sites through its interaction with the GluR1 subunit.